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Two-dimensional (2D) "graphene-like" inorganic materials, because of the short lithium ion diffusion path and unique 2D carrier pathways, become a new research focus of the lithium storages. Some "graphene-like" binary compounds, ...
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Two-dimensional (2D) "graphene-like" inorganic materials, because of the short lithium ion diffusion path and unique 2D carrier pathways, become a new research focus of the lithium storages. Some "graphene-like" binary compounds, such as, MnO2, MoS2 and VO2 ultrathin nanosheets, have been synthesized by the peeling method, which also exhibit enhanced lithium storage performances. However, it still remains a great challenge to synthesize widely-used lithium-containing ternary oxides with "graphene-like" nanostructures, because the lithium-containing ternary oxides, unlike ternary layered double hydroxides (LDH), are very hard to be directly peeled. Herein, we successfully synthesized ultrathin Li3VO4 nanoribbons with a thickness of about 3 nm by transformation from ultrathin V2O5 xH(2)O nanoribbons, moreover, we achieved the preparation of ultrathin Li3VO4 nanoribbon@graphene sandwich-like nanostructures (LVO/G) through the layer-by-layer assembly method. The unique sandwich-like nanostructures shows not only a high specific reversible capacitance (up to 452.5 mA h g(-1) after 200 cycles) but also an excellent cycling performance (with more than 299.2 mA h g(-1) of the capacity at 10C after 1000 cycles) as well as very high rate capability. Such template strategy, using "graphene-like" binary inorganic nanosheets as templates to synthesize lithium-containing ternary oxide nanosheets, may be extended to prepare other ternary oxides with "graphene-like" nanostructures. (C) 2015 Elsevier Ltd. All rights reserved.
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A novel sandwich-like structure was first proposed to adjust the electrical properties of NTC thermistors. The LaCr0.7Fe0.3O3-NiMn2O4 supported composite ceramics with sandwich-like structure were initially fabricated via traditio...
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A novel sandwich-like structure was first proposed to adjust the electrical properties of NTC thermistors. The LaCr0.7Fe0.3O3-NiMn2O4 supported composite ceramics with sandwich-like structure were initially fabricated via traditional solid-state reaction and uniaxial pressing methods, which allowed for the advantages of each component to be integrated into one material. X-Ray diffraction analysis indicates the ceramics mainly consisting of orthorhombic perovskite LaCr0.7Fe0.3O3 and cubic spinel NiMn2O4 phases. SEM images manifest that the three layers adhered well to each other and exhibited high density. For electrical properties, the ?25?C was expanded to a wide range of 1182?110,233 ??cm and could be adjusted to the desired values by tuning the volume ratio of two basic layers, the B value was enhanced from 3358 K to 4167 K by NiMn2O4, and the thermal stability was improved by LaCr0.7Fe0.3O3 with a resistance shift less than 0.55 % after annealing at 150 ?C for 1500 h.
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Sandwich-like metal complexes (Tpyb)_2M (M = Mg, Fe, Mn) that are based on the novel t-butylphenyltris(2-pyridyl)borate ligand were prepared and fully characterized by multinuclear NMR spectroscopy, high-resolution matrix-assisted...
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Sandwich-like metal complexes (Tpyb)_2M (M = Mg, Fe, Mn) that are based on the novel t-butylphenyltris(2-pyridyl)borate ligand were prepared and fully characterized by multinuclear NMR spectroscopy, high-resolution matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, and single crystal X-ray crystallography. The unique steric and electronic nature of the Tpyb ligand led to structural parameters and properties that are quite different to those of previously reported tris(pyrazolyl)borate and tris(2-pyridyl)aluminate complexes. Most importantly, depending on the crystallization procedure, supramolecular structures could be generated with relatively smaller (ca. 4-5 ?) or larger (ca. 8 ?) diameter pores propagating throughout the crystal lattice. Although the supramolecular structures are held together only by weak intermolecular C-H?π interactions, the solvent in the larger channels could be completely removed without any loss of crystallinity or degradation of the framework. Surface area and gas uptake measurements on the Mg complex further confirmed the permanent porosity, while the calculated non-localized density functional theory (NLDFT) pore diameter of 8.6 ? proved to be in excellent agreement with that obtained from single crystal X-ray crystallography. Our new materials are remarkably thermally stable as degradation did not occur up to about 400 C based on thermogravimetric analysis (TGA), and a sample of the Mg complex showed no loss of crystallinity even after heating to 140 C under high vacuum for 72 h according to single crystal X-ray diffraction data.
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The effect of the use of sandwich-like polyaniline (S-PANI) nanocomposites in CO2 gas-separation membranes was investigated. S-PANI nanocomposites were synthesized via a two-step dispersion polymerization method. The first step wa...
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The effect of the use of sandwich-like polyaniline (S-PANI) nanocomposites in CO2 gas-separation membranes was investigated. S-PANI nanocomposites were synthesized via a two-step dispersion polymerization method. The first step was to manufacture a leaf-like polyaniline (L-PANI), which was used in the next step as a 2D template to synthesize the S-PANI. SEM images show that a three-layer sandwich-like structure of the S-PANI was successfully synthesized. ATR-FTIR measurements revealed that the S-PANI has a structure with conductive PANI layers on both sides of the L-PANI template. Furthermore, the N-2 and CO2 adsorption isotherms illustrate that S-PANI is much more attractive to CO2 than N-2 because of the amine functional groups of S-PANI. Hence, the CO2/N-2 separation performance of the ethylene vinyl acetate (EVA) copolymer membrane was successfully enhanced by the addition of the S-PANI nanocomposite. The CO2/N-2 selectivity of the membrane increased from 6.8 to 32.5 with a 3-wt% loading of S-PANI within the EVA matrix. The results show that 2D S-PANI could feasibly be used for CO2 gas membrane separation. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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Sandwich-like, hetero-structured vanadium pentoxide/carbon nanotubes are prepared by incorporating modified carbon nanotubes (CNTs) into layered V2O5 sheets via a simple hydrothermal method. The CNTs ensure fast and smooth electro...
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Sandwich-like, hetero-structured vanadium pentoxide/carbon nanotubes are prepared by incorporating modified carbon nanotubes (CNTs) into layered V2O5 sheets via a simple hydrothermal method. The CNTs ensure fast and smooth electron transfer between V2O5 sheets, leading to higher electrochemical performance compared with V2O5 sheets and bulk V2O5. As a result, the specific capacitance of the V2O5/CNTs complex reaches a value of 553.33 F g(-1). The composite also exhibits good cycling stability and maintains 83% of original capacitance over 1000 cycles at 10 mA cm(-2). (C) 2017 Elsevier B. V. All rights reserved.
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Sandwich-like BiVO4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG 10000) using a facile microwave-assis...
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Sandwich-like BiVO4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG 10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N-2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO4 sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO4 sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (lambda >= 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO4 sheets can be attributed to its large surface area over the irregular BiVO4 particles. (C) 2016 Elsevier B.V. All rights reserved.
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The structures of sandwich-like and chain-like superatom compounds Li-3-N-4-M-3 (M = Li, Na and K) are obtained at the MP2/6-311+G(2d) level. These structures are stable own to large interaction energy ranging from -184.4 to -236....
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The structures of sandwich-like and chain-like superatom compounds Li-3-N-4-M-3 (M = Li, Na and K) are obtained at the MP2/6-311+G(2d) level. These structures are stable own to large interaction energy ranging from -184.4 to -236.9 kcal/mol. Maximum nucleus-independent chemical shift (NICSmax) values of M-3(+) are located at the outside of the M-3(+) ring plane about 0.6-1.5 angstrom for the sandwich-like structures, which exhibit unusual out-of-plane sigma-aromaticity. The NICSmax Values of N-4(2-) in the sandwich-like structures are obviously larger than that of corresponding chain-like structures. which show that the two adjacent rings (Li-3(+) and M-3(+)) enhance the aromaticity of N-4(2-) ring in the sandwich-like structures. In addition, the N-4 in the superatom compound is proposed as a new "supersulfur" atom.
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A NiFe-based compound is considered one of the most promising candidates for the highest oxygen evolution reaction (OER) electrocatalytic activities among all nonprecious metal-based electrocatalysts. In this report, a unique cata...
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A NiFe-based compound is considered one of the most promising candidates for the highest oxygen evolution reaction (OER) electrocatalytic activities among all nonprecious metal-based electrocatalysts. In this report, a unique catalyst of free-standing sandwiched NiFe nanoparticles encapsulated by graphene sheets is first devised and fabricated. In this method, we use low-cost, sustainable, and environmentally friendly glucose as a carbon source, ultrathin Fe-doped Ni(OH)(2) nanosheets as a precursor, and a sacrificial template. This special nanoarchitecture with a conductive network around active catalysts can accelerate electron transfer and prevent NiFe nanoparticles from aggregation and peeling off during long-time electrochemical reactions, thereby exhibiting an excellent OER activity and stability in basic solutions. In this work, our sandwiched catalyst presents well activities of a low onset of similar to 1.44 V (vs RHE) and Tafel slope of similar to 30 mV/decade in 1 M KOH at a scan rate of 5 mV/s.
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Two heteropolyoxotungstates, K_4Na_4[Cu_2(H_2O)_8Cu_4(H_2O)_2(B-alpha-GeW_9O_(34))]l4H_2O (1) and K_8[Cu_2(H_2O)_8Cu_4(H_2O)_2(B-alpha-SiW_9O_(34))_2]4H_2O (2), have been obtained in aqueous solution and characterized by 1R, TG, e...
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Two heteropolyoxotungstates, K_4Na_4[Cu_2(H_2O)_8Cu_4(H_2O)_2(B-alpha-GeW_9O_(34))]l4H_2O (1) and K_8[Cu_2(H_2O)_8Cu_4(H_2O)_2(B-alpha-SiW_9O_(34))_2]4H_2O (2), have been obtained in aqueous solution and characterized by 1R, TG, elemental analysis, magnetism, and single-crystal X-ray analysis. The two compounds are one-dimensional (1-D) inorganic polymers composed of Cu-containing sandwich polyoxoanions, linked by additional Cu~(2+) ions to construct 1-D ladder-like chain structures. To the best of our knowledge, it is the first example of a 1-D ladder-like chain based on sandwich-type anions and Cu~(2+) linkers. Furthermore, the chains in 1 are further connected by K~+ into an extensive three-dimensional (3-D) framework. The magnetic studies of 1 indicate that antiferromagnetic interactions exist in the central tetra-metal set of the sandwich-type polyoxoanion.
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